Blood cells play a crucial part in maintaining the health and viability of animals, including humans. White blood cells include neutrophils, macrophage, eosinophils and basophils/mast cells as well the B and T cells of the immune system. White blood cells are continuously replaced via the hematopoietic system, by the action of colony stimulating factors (CSF) and various cytokines on stem cells and progenitor cells in hematopoietic tissues. The nucleotide sequences encoding a number of these growth factors have been cloned and sequenced. Perhaps the most widely known of these is granulocyte colony stimulating factor (G-CSF) which has been approved for use in counteracting the negative effects of chemotherapy by stimulating the production of white blood cells and progenitor cells (peripheral blood stem cell mobilization). A discussion of the hematopoietic effects of this factor can be found, for example, in U.S. Pat. No. 5,582,823, incorporated herein by reference.
Several other factors have been reported to increase white blood cells and progenitor cells in both human and animal subjects. These agents include granulocyte-macrophage colony stimulating factor (GM-CSF), Interleukin-1 (IL-1), Interleukin-3 (IL-3), Interleukin-8 (IL-8), PIXY-321 (GM-CSF/IL-3 fusion protein), macrophage inflammatory protein, stem cell factor, thrombopoietin and growth related oncogene, as single agents or in combination (Dale, D., et al., Am. J. of Hematol. (1998) 57:7-15; Rosenfeld, C., et al., Bone Marrow Transplantation (1997) 17:179-183; Pruijt, J., et al., Cur. Op. in Hematol. (1999) 6:152-158; Broxmeyer, H., et al., Exp. Hematol. (1995) 23:335-340; Broxmeyer, et al., Blood Cells, Molecules and Diseases (1998) 24:14-30; Glaspy, J., et al., Cancer Chemother. Pharmacol. (1996) 38 (suppl): S53-S57; Vadhan-Raj, S., et al., Ann. Intern. Med. (1997) 126:673-81; King, A., et al., Blood (2001) 97:1534-1542; Glaspy, J., et al., Blood (1997) 90:2939-2951).
While endogenous growth factors are pharmacologically effective, the well known disadvantages of employing proteins and peptides as pharmaceuticals underlies the need to add to the repertoire of such growth factors with agents that are small molecules. In another aspect, such small molecules are advantageous over proteins and peptides where production in large quantities are desired.
A number of cyclic polyamine antiviral agents have been described in a series of U.S. patents and applications over the last several years. These patents, U.S. Pat. Nos. 5,021,409; 6,001,826; 5,583,131; 5,698,546; and 5,817,807 are incorporated herein by reference. Also incorporated by reference are PCT publications WO 00/02870 based on an application filed 8 Jul. 1998 and WO 01/44229, based on an application filed 17 Dec. 1999, which describe additional compounds. These publications describe the structural characteristics of the cyclic polyamine antiviral agents.
The structural characteristics of a number of non-cyclic amine antiviral agents have also been described in a series of U.S. applications, now published as PCT publications. These publications, WO 00/56729, based on an application filed 24 Mar. 2000; WO 02/22600, based on applications filed 15 and 20 Sep. 2000; WO 02/22599, based on applications filed 15 and 22 Sep. 2000 as well as WO 02/34745 published 2 May 2002, are incorporated herein by reference in their entirety.
In addition, improved methods for preparation of some of the cyclic polyamine compounds are described in U.S. Pat. Nos. 5,612,478; 5,756,728; 5,801,281; and 5,606,053 and PCT publication WO 02/26721, based on an application filed 29 Sep. 2000. The disclosures of these U.S. documents are also incorporated herein by reference in their entirety.
We have previously found, and have disclosed in PCT publication WO 02/58653, based on an application filed 1 Feb. 2000, that some of the polyamine antiviral agents described in the above mentioned publications have the effect of increasing the white blood cell count. It has now been found that the polyamine antiviral agents described in the above-mentioned publications also have the effect of increasing progenitor cells and/or stem cells.
The development and maturation of blood cells is a complex process. Mature blood cells are derived from hematopoietic precursor cells (progenitor) cells and stem cells present in specific hematopoietic tissues including bone marrow. Within these environments hematopoietic cells proliferate and differentiate prior to entering the circulation. The chemokine receptor CXCR4 and its natural ligand stromal cell derived factor-1 (SDF-1) appear to be important in this process (for reviews see Maekawa, T., et al., Internal Med. (2000) 39:90-100; Nagasawa, T., et al., Int. J. Hematol. (2000) 72:408-411). This is demonstrated by reports that CXCR4 or SDF-1 knock-out mice exhibit hematopoietic defects (Ma, Q., et al., Proc. Natl. Acad. Sci USA (1998) 95:9448-9453; Tachibana, K., et al., Nature (1998) 393:591-594; Zou, Y-R., et al., Nature (1998) 393:595-599). It is also known that CD34+ progenitor cells express CXCR4 and require SDF-1 produced by bone marrow stromal cells for chemoattraction and engraftment (Peled, A., et al., Science (1999) 283:845-848) and that in vitro, SDF-1 is chemotactic for both CD34+ cells (Aiuti, A., et al., J. Exp. Med. (1997) 185:111-120; Viardot, A., et al., Ann. Hematol. (1998) 77:194-197) and for progenitor/stem cells (Jo, D-Y., et al., J. Clin. Invest. (2000) 105:101-111). SDF-1 is also an important chemoattractant, signaling via the CXCR4 receptor, for several other more committed progenitors and mature blood cells including T-lymphocytes and monocytes (Bleul, C., et al., J. Exp. Med. (1996) 184:1101-1109), pro-and pre-B lymphocytes (Fedyk, E. R., et al., J. Leukoc. Biol. (1999) 66:667-673; Ma, Q., et al., Immunity (1999) 10:463-471) and megakaryocytes (Hodohara, K., et al., Blood (2000) 95:769-775; Riviere, C., et al., Blood (1999) 95:1511-1523; Majka, M., et al., Blood (2000) 96:4142-4151; Gear, A., et al., Blood (2001) 97:937-945; Abi-Younes, S., et al., Circ. Res. (2000) 86:131-138).
Thus, in summary, it appears that SDF-1 is able to control the positioning and differentiation of cells bearing CXCR4 receptors whether these cells are stem cells (i.e., cells which are CD34+) and/or progenitor cells (which result in formation of specified types of colonies in response to particular stimuli; that can be CD34+ or CD34−) or cells that are somewhat more differentiated.
Recently, considerable attention has been focused on the number of CD34+ cells mobilized in the pool of peripheral blood progenitor cells used for autologous stem cell transplantation. The CD34+ population is the component thought to be primarily responsible for the improved recovery time after chemotherapy and the cells most likely responsible for long-term engraftment and restoration of hematopoiesis (Croop, J. M., et al., Bone Marrow Transplantation (2000) 26:1271-1279). The mechanism by which CD34+ cells re-engraft may be due to the chemotactic effects of SDF-1 on CXCR4 expressing cells (Voermans, C., Blood, 2001, 97, 799-804; Ponomaryov, T., et al., J. Clin. Invest. (2000) 106:1331-1339). More recently, adult hematopoietic stem cells were shown to be capable of restoring damaged cardiac tissue in mice (Jackson, K., et al., J. Clin. Invest. (2001) 107:1395-1402; Kocher, A., et al., Nature Med. (2001) 7:430-436).
Thus, the role of the CXCR4 receptor in managing cell positioning and differentiation has assumed considerable significance.
Citation of the above documents is not intended as an admission that any of the foregoing is pertinent prior art. All statements as to the date or representation as to the contents of these documents is based on the information available to the applicants and does not constitute any admission as to the correctness of the dates or contents of these documents. Further, all documents referred to throughout this application are incorporated in their entirety by reference herein.